This invention relates generally to liquid transferring devices, and more particularly to improvements in hand-held micropipettors that result in increased accuracy of the amount of liquid so transferred.
Within the last few years, hand-held micropipettors have become very popular as laboratory instruments, primarily in medical laboratories. The following United States patents describe existing instruments supplied by Oxford Laboratories Inc., the assignee of the present application: U.S. Pat. Nos. RE 27,637 -- Roach (1973); 3,855,867 -- Roach (1974); 3,882,729 -- Roach (1975); and 3,918,308 -- Reed (1975).
Such devices include a tube-like barrel body structure having a plunger assembly extending outward of one end thereof and a piston attached to the other end of the plunger and positioned within a piston chamber. The piston chamber is maintained in fluid communication with an aperture at an end of the barrel handle which is shaped for frictionally engaging a detachable tip. The piston is held in a normal rest position by one or more springs within the barrel handle. When used to transfer liquid, the pipettor plunger is depressed, the attached tip is placed in a liquid and the plunger released to draw a precise amount of liquid into the tip. An air interface exists between the piston and liquid. The pipettor is then removed to a container for discharge of the liquid. The liquid is discharged from the tip by again depressing the plunger.
As the popularity and applications of hand-held micropipettors increases, their users are demanding the highest degree of accuracy in volumes of liquid transferred thereby. Therefore, it is a principal object of the present invention to provide a hand-held micropipettor with increased accuracy and repeatability.
Users of such instruments are also demanding added convenience in maintenance and operation. Therefore, it is another object of the present invention to provide an improved hand-held micropipettor with increased convenience of use and maintenance.